Elliptical tank structure for oil circuit breakers



Aug. 20, 1968 J. R. M CLOUD ELLIPTICAL TANK STRUCTURE FOR OIL CIRCUIT BREAKERS Filed Jan. 6, 71966 Q 3/ Q G if Z4 5; 25 6.5 25

Jfl/ J4 53 2! 27 United States Patent 3,398,247 ELLIPTICAL TANK STRUCTURE FOR OIL CIRCUIT BREAKERS James R. McCloucl, Burbank, Calif., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Jan. 6, 1966, Ser. No. 519,032 Claims. (Cl. 200-150) This invention relates to oil circuit breakers, and more specifically relates to the securement of support structures to elliptical tanks at a point of substantially zero flexure of these tanks due to changes in internal pressure.

Oil circuit breakers are well known to the art and comprise suitable interrupter structures which are positioned Within a steel tank which is filled with oil. This oil is used as the means for extinguishing arcs drawn within the interrupters during circuit interruption operation, and to provide a high dielectric strength for the interrupter.

During the operation of an oil circuit breaker, gas under high pressure is generated within the tank which is hermetically sealed. The tank walls must be sufiieiently strong to withstand this pressure.

In order to reduce the volume of oil required in such tanks, it is common practice where two interrupters connected in parallel are contained within a common tank to make the tank elliptical in shape with the interrupters lying along the major axis of the ellipse and extending parallel to the foci of the ellipse. By using an elliptical arrangement, the tank volume is decreased when compared to an equivalent circular cross-section tank.

Moreover, the elliptical tank provides a certain amount of stress relief during interruption operation by the flexure of the generally elongated wall sections extending along the major axis of the ellipse to provide a bellows-like effect.

Major problems are encountered when using the elliptical tank, however, because of this flexure of the tank walls. Thus, it is necessary to secure support braces to the tank, especially where a plurality of tanks are contained together in a multiphase assemblage, and it is necessary to mechanically connect an operating mechanism housing which extends to the tank for operating the interrupter structures.

The principle of the present invention is to make all mechanical connections from fixed structures external of an elliptical tank to a point of zero flexure of the elliptical tank. That is to say, it has been recognized that there are four points on the elliptical section of the tank which will not undergo movement during expansion of the major length of the tank walls. Thus, when high pressure is generated within the elliptical tank, the major length of the walls expand, while the minor surface lengths will contract. I have found that this expansion and contraction will occur about four parallel lines parallel to the foci of the ellipse and lying on the elliptical surface, which sections remain fixed in space, or have zero lateral movement, when the tank walls expand and contract.

In accordance with the invention, all support structures are connected along these pivotal points of substantially zero lateral movement on the ellipse so that structural support problems of mounting a fixed structure on a movable surface are eliminated.

Accordingly, a primary object of this invention is to provide a novel structure for mounting fixed components to an elliptical oil circuit breaker tank.

Another object of this invention is to simplify mechanical structural problems in connecting stationary structures to an elliptical circuit breaker tank.

3,398,247 Patented Aug. 20, 1968 These and other objects of this invention will become apparent from the following description when taken in connection with the drawings, in which:

FIGURE 1 schematically illustrates an elliptical circuit breaker tank and illustrates the manner in which it will expand under high internal pressures.

FIGURE 2 is a side plan view of a three-phase interrupter system using elliptical oil circuit breaker tanks and incorporating the present invention.

FIGURE 3 is a top view of FIGURE 2.

Referring first to FIGURE 1, I have illustrated therein, in a schematic fashion, the elliptical shape of an oil circuit breaker tank 10. As indicated above, the oil circuit breaker tank 10 will contain therein an interrupter structure schematically illustrated in FIGURE 1 as cooperating contacts 11 and 12 which are connected in series, and respectively include stationary and movable contacts which are movable between engaged and disengaged positions. Suitable external electrical terminals 13 and 14 are brought outside of the tank 10* as by standard insulation bushings so that external connection can be made to the circuit interrupters 11 and 12.

The circuit interrupters 11 and 12 are immersed in oil contained within tank 10 which is used to aid in the interruption of arcs drawn by contacts 11 and 12 during interruption operation. At the same time, however, substantial pressures are generated within tank 10 which will cause the tank, when made elliptical as in FIGURE 1 in order to conserve oil, to expand to the dotted line position shown.

Because of the expansion of the walls of elliptical tank 10, it has been a serious problem in the past to connect fixed structural components to the tank walls. I have recognized that during the expansion of tank 10 there will be four points 15, 16, 17 and 18, illustrated by cross-marks in FIGURE 1, which will experience substantially zero lateral movement. The precise location of these points will be exactly determined by the details of the construction of the tank wall including its thickness and its specific configuration, although generally these points will lie in a plane which approximately includes the respective foci F and P of the elliptical shape. Thus, zero flexure points 15 and 18 are generally in a plane which approximately includes focus F while points 16 and 17 lie in a plane which generally includes focus F After recognizing this phenomenon, and in accordance with the invention, all fixed structural connections can now be made to one of the zero flexure points 15 through 18 so that, during circuit interruption operation, the fixed structural connection will not experience any substantial movement as would a connection made, for example, along the major or minor axis of the ellipse.

FIGURES 2 and 3 illustrate one manner in which the invention has been applied to a multiphase circuit interrupter.

Referring now to FIGURES 2 and 3, I have illustrated therein three elliptical tanks 20, 21 and 22 which each contain therein two series connected interrupters for their respective phase. Circuit connections are made to the interrupters through suitable insulator bushings, shown as insulator bushings 23-24, 25-26 and 27-28 for tanks 20 through 22, respectively.

Each of the tanks 20 through 22 are then supported on a bottom structural steel frame or pad 30, and are provided with upper V-shaped cross braces 31, 32, 33 and 34. The cross braces 31 and 32 extend between tanks 20 and 21, and abut at their apex, as shown. The outer ends of V-shaped braces 31 and 32 are then welded to tanks 20 and 21 at points 40 and 41 on tank 20 and at points 42 and 43 on tank 21. The points 40 through 43 correspond to zero flexure points for each of tanks 20 and 21, in accordance with the invention.

Thus, if one or both of the interrupter systems within tanks 20 and 21 is operated so that the high pressure gases generated within the tanks cause flexure of their walls, there will be no flexure at the points to which structural braces 31 and 32 are connected so that there will not be any stress applied to cross braces 31 or 32 due to this movement.

Cross braces 33 and 34 similarly are provided between tanks 21 and 22, and are connected at zero flexure points 45, 46, 47 and 48 on the tanks 21 and 22. Clearly, this connection will be subject only to the limited rotational movement of the elliptical tank walls about their point of zero lateral movement, as shown in FIGURE 1. This limited rotational movement, however, can be easily sustained by a good welded connection at these zero flexure points.

As is common knowledge in the oil circuit breaker interrupter art, and for an installation such as that shown in FIGURES 2 and 3, it is necessary to provide an operating mechanism 50 which is supported in part from the pad or frame 30 as by support member 51, as well as to support the operating mechanism 50 from the tank 20.

In accordance with the invention, support arms such as arms 52 and 53 extending from each side of control housing 50 are welded to tank 20 at the zero flexure points 54 and 55 of the tank 20. Thus, the operating mechanism 50, which is necessarily stationarily positioned, will not be subject to any forces tending to move the operating mechanism 50 due to flexure of the tank walls.

a Note that the operating mechanism 50 will have an output shaft 60 which extends through motion-transmitting housing 61 which has an output shaft 62 connected to each of the interrupters within tanks 20, 21 and 22 through the mechanism pick-ofi' housings 63, 64 and 65 through which the shaft 62 extends. A typical example of operating mechanism 50 may be found in US. Patent 3,187,593..

Accordingly, the operating mechanism will remain completely stationary even though the tank Walls of tanks 20, 21 and 22 expand due to the internal pressures generated during the operation of their respective interrupters.

Although this invention has been described with respect to its preferred embodiments, it shoud be understood that many variations and modifications will now be obvious to those" skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. In combination; an oil filled tank, interrupter means contained within said tank, and an operating mechanism housing connected to the exterior of said oil filled tank; said oil filled tank being elliptical in cross-section; said elliptical tank being laterally expansible responsive to internal pressure caused by the operation of said interrupter means and having at least one line along the height thereof which experiences substantially zero lateral movement as said tank walls are expanded by said internal pressure; structural support means extending from said tank to said mechanism housing; said structural support means connected to said tank at approximately said line of zero lateral movement.

2. The device as set forth in claim 1 wherein said mechanism housing and tank are connected to a common fixed bottom support; said mechanism housing having an operating shaft extending therefrom and into the top of said tank.

3. The device as set forth in claim 1 wherein said elliptical tank has four parallel lines of substantially zero lateral movement; two of said four parallel lines lying in a plane closely located to the'first focus of said elliptical tank, the other two of said four parallel lines being in a plane closely located to the second focus of said elliptical tank.

4. The device as set forth in claim 1 which includes a second elliptical tank identical to said elliptical tank adjacent to and spaced from said elliptical tank; the major axes of said elliptical tank and second elliptical tank being parallel to one another; and cross brace support means extending between said elliptical tank and said second eliptical tank; said cross brace support means connected at either end to said line of zero lateral movement in said elliptical tank and said second elliptical tank.

5. In combination; an elliptical tank and a second elliptical tank; each of said tanks including pressure generating means therein; a common fixed bottom support for said tanks; each of said tanks being identical to one another and each having four parallel lines of substantially zero lateral movement during fiexure of the walls of said tanks due to generation of pressure therein; and cross brace support means extending between said tanks; said cross brace support means ends connected to said tanks at at least one of their said respective lines of zero lateral movement.

I References Cited UNITED STATES PATENTS 1,859,969 5/1932 Jansson 200- 2,792,477 5/1957 MacNeill et a1. 200150 3,179,776 4/1965 Wall et a1. 200-150 ROBERT S. MACON, Primary Examiner. 

1. IN COMBINATION; AND OIL FILLED TANK, INTERRUPTER MEANS CONTAINED WITHIN SAID TANK, AND AN OPERATING MECHANISM HOUSING CONNECTED TO THE EXTERIOR OF SAID OIL FILLED TANK; SAID OIL FILLED TANK BEING ELLIPTICAL IN CROSS-SECTION; SAID ELLIPTICAL TANK BEING LATERALLY EXPANSIBLE RESPONSIVE TO INTERNAL PRESSURE CAUSED BY THE OPERATION OF SAID INTERRUPTER MEANS AND HAVING AT LEAST ONE LINE ALONG THE HEIGHT THEREOF WHICH EXPERIENCES SUBSTANTIALLY ZERO LATERAL MOVEMENT AS SAID TANK WALLS ARE EXPANDED BY SAID INTERNAL PRESSURE; STRUCTURAL SUPPORT MEANS EXTENDING FROM SAID TANK TO SAID MECHANISM HOUSING; SAID STRUCTURAL SUPPORT MEANS CONNECTED TO SAID TANK AT APPROXIMATELY SAID LINE OF ZERO LATERAL MOVEMENT. 